Bitcoin Payment button to charge the buyer AND get a commission fee for myself

[tipona]

Hello,
I want to set up a bitcoin payment button on my marketplace website, for example via bitPay, but when a buyer buys someone's article from a seller I want the buyer to ALSO pay a fee which will be returned to my bitcoin address.
How to make this possible ?
Thanks in advance!

[ranochigo]

It might not be so economical, if the fees are low. Each of the outputs contribute significantly to the fees and it might not be worth it to collect the fees individually, rather than have the merchant pay you during the settlement.

BIP70 allows the merchant to specify multiple output as part of the payment request. You can perhaps try to explore that further. I'm not sure about the multiple output compatibility with the wallets though, IIRC it is allowed as per the proposal.

[odolvlobo]

Hello,
I want to set up a bitcoin payment button on my marketplace website, for example via bitPay, but when a buyer buys someone's article from a seller I want the buyer to ALSO pay a fee which will be returned to my bitcoin address.
How to make this possible ?
Thanks in advance!

The problem is that the sender creates the transaction. There are protocols, such as BIP 70 mentioned by ranchigo, that describe how to make a payment, but the sender's wallet must support the protocol in order to create the proper transaction.

[NeuroticFish]

Last time I've used BitPay it was them creating the invoice the user has to pay. And I don't think that BitPay will allow others interfere with this.
So if OP has some really big plans, he may have to convince BitPay do this change at their side.
Am I wrong?